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Re: [Discuss-gnuradio] WBX <70MHz

From: Matt Ettus
Subject: Re: [Discuss-gnuradio] WBX <70MHz
Date: Wed, 02 Jun 2010 14:29:20 -0700
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv: Gecko/20100430 Fedora/3.0.4-2.fc12 Thunderbird/3.0.4

On 06/02/2010 02:06 PM, John Orlando wrote:
On Wed, Jun 2, 2010 at 3:54 PM, Sharif Shaher<address@hidden>  wrote:

I am trying to tune the WBX to 60MHz, but everytime I do
I get an error.  If I do it through usrp2_fft.py it says "Failed",
if I do it through my c++ code, I get the error
set_rx_center_freq(6e+07) failed.

According to the driver, located at
gnuradio/usrp2/firmware/lib/db_wbxng.c, the minimum supported
frequency is 68.75 MHz, which makes sense since the ADF4350
synthesizer used on the WBX board only is spec'ed to run down to 137.5
MHz (and the quad demod chip on the WBX divides this in half

That being said, these VCOs can typically be tuned lower in frequency
(or higher) than the min/max frequency specs, but you'll likely see
additional phase noise, and you'll be running outside the expected
operating range of the chip, which is generally not ideal.  But it can
be done.

No, we just tune to the lowest specified frequency for the VCO/PLL chip, and the rest of the tuning is done using the DDC/DUC. Everything is used within specs.


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